1. Field of the Invention
The present invention generally relates to image processing apparatuses, image processing methods, and recording media. More particularly, the invention relates to an image processing apparatus and an image processing method in which information can be embedded in an image with a minimal level of degradation of the quality of reproduced images and without increasing the amount of data.
2. Description of the Related Art
One of the techniques of embedding information without increasing the amount of data is to convert the least significant bit (LSB) or the lower two bits of, for example, digital audio data into information to be embedded. In this technique, the lower bits of digital audio data, which do not significantly influence the sound quality, are simply substituted for the information to be embedded. Accordingly, when the digital audio data is reproduced, it is output as it is without restoring the lower bits into the original state. More specifically, since it is difficult to restore the lower bits embedded with information into the original state, and also, since the lower bits do not significantly influence the sound quality, the digital audio data is output while containing information embedded therein.
According to the above-described technique, however, a signal different from the original signal is disadvantageously output, which, to some degree, affects the sound quality if the signal is audio data, or influences the image quality if the signal is video data.
Accordingly, in view of the above background, it is an object of the present invention to embed information in an image with a minimal level of degradation of the image quality and without increasing the amount of data.
In order to achieve the above object, according to one aspect of the present invention, there is provided an image processing apparatus for performing processing for embedding information in an image. The apparatus includes selection means for selecting a pixel of the image. Processing means performs processing on the pixel selected by the selection means according to the information so that the pixel is reproducible by utilizing a correlation of the image, thereby embedding the information in the pixel.
According to another aspect of the present invention, there is provided an image processing method for performing processing for embedding information in an image. The method includes a selection step of selecting a pixel of the image, and a processing step of performing processing on the pixel selected in the selection step according to the information so that the pixel is reproducible by utilizing a correlation of the image, thereby embedding the information in the pixel.
According to still another aspect of the present invention, there is provided a providing medium for providing a computer program for enabling a computer to perform processing for embedding information in an image. The computer program includes a selection step of selecting a pixel of the image, and a processing step of performing processing on the pixel selected in the selection step according to the information so that the pixel is reproducible by utilizing a correlation of the image, thereby embedding the information in the pixel.
According to a further aspect of the present invention, there is provided a providing medium for providing an information-embedded image in which information is embedded. The information-embedded image is obtained by embedding the information in the image by selecting a pixel of the image, and by performing processing on the selected pixel according to the information so that the pixel is reproducible by utilizing a correlation of the image.
According to a further aspect of the present invention, there is provided an image processing apparatus for performing processing for decoding an information-embedded image into an original image and original information. The apparatus includes selection means for selecting a pixel of the image-embedded information. Processing means performs predetermined processing on the pixel selected by the selection means. Correlation calculation means calculates a first correlation between the pixel selected by the selection means and a peripheral pixel around the selected pixel, and calculates a second correlation between the pixel selected by the selection means and processed by the processing means and the peripheral pixel around the pixel. Comparison means compares the first correlation and the second correlation. Decoding means decodes the pixel selected by the selection means and the information embedded in the pixel based on a result obtained by the comparison means.
According to a yet further aspect of the present invention, there is provided an image processing method for performing processing for decoding information-embedded image into an original image and original information. The method includes a selection step of selecting a pixel of the information-embedded image, a processing step of performing predetermined processing on the pixel selected in the selection step, a correlation calculation step of calculating a first correlation between the pixel selected in the selection step and a peripheral pixel around the selected pixel and calculating a second correlation between the pixel selected in the selection step and processed in the processing step and the peripheral pixel around the pixel, a comparison step of comparing the first correlation and the second correlation, and a decoding step of decoding the pixel selected in the selection step and the information embedded in the pixel based on a result obtained in the comparison step.
According to a further aspect of the present invention, there is provided a providing medium for providing a computer program for enabling a computer to perform processing for decoding information-embedded image into an original image and original information. The computer program includes a selection step of selecting a pixel of the information-embedded image, a processing step of performing predetermined processing on the pixel selected in the selection step, a correlation calculation step of calculating a first correlation between the pixel selected in the selection step and a peripheral pixel around the selected pixel and calculating a second correlation between the pixel selected in the selection step and processed in the processing step and the peripheral pixel around the pixel, a comparison step of comparing the first correlation and the second correlation, and a decoding step of decoding the pixel selected in the selection step and the information embedded in the pixel based on a result obtained in the comparison step.
According to a further aspect of the present invention, there is provided an image processing apparatus including a transmitter for transmitting an information-embedded image obtained by embedding information and a receiver for receiving the information-embedded image from the transmitter and for decoding the image. The transmitter includes first selection means for selecting a pixel of the image. First processing means performs processing on the pixel selected by the first selection means according to the information so that the pixel is reproducible by utilizing a correlation of the image, thereby embedding the information in the pixel and outputting the information-embedded image. The receiver includes second selection means for selecting a pixel of the information-embedded image. Second processing means performs predetermined processing on the pixel selected by the second selection means. Correlation calculation means calculates a first correlation between the pixel selected by the second selection means and a peripheral pixel around the selected pixel and calculates a second correlation between the pixel selected by the second selection means and processed by the second processing means and the peripheral pixel around the pixel. Comparison means compares the first correlation and the second correlation. Decoding means decodes the pixel selected by the second selection means and the information embedded in the pixel based on a result obtained by the comparison means.
According to a further aspect of the present invention, there is provided an image processing method for use in an image processing apparatus including a transmitter for transmitting an information-embedded image obtained by embedding information and a receiver for receiving the information-embedded image from the transmitter and for decoding the image. The method includes the steps of selecting a pixel of the image by the transmitter, performing processing by the transmitter on the selected pixel according to the information so that the pixel is reproducible by utilizing a correlation of the image, thereby embedding the information in the pixel and outputting the information-embedded image, selecting the pixel of the information-embedded image by the receiver, performing predetermined processing by the receiver on the selected pixel, calculating by the receiver a first correlation between the pixel selected from the information-embedded image and a peripheral pixel around the selected pixel and calculating a second correlation between the pixel selected from the information-embedded image and undergone the predetermined processing and the peripheral pixel around the pixel, comparing the first correlation and the second correlation by the receiver, and decoding the pixel selected from the information-embedded image and the information embedded in the pixel by the receiver based on a result of comparison.